WASHINGTON — A procalcitonin-guided protocol can cut the duration of antibiotic use in patients with community-acquired pneumonia by roughly 50%, according to data presented at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
“Procalcitonin seems to be a more reliable parameter for the individual tailoring and discontinuation of antibiotics as compared with commonly and routinely used clinical and laboratory parameters,” said Dr. Mirjam Christ-Crain, an endocrinologist at the University Hospital Basel (Switzerland).
She and her colleagues proposed using procalcitonin as a biomarker to guide antibiotic treatment because the propeptide of calcitonin is increased with increasing severity of bacterial infection.
For this study, patients with community-acquired pneumonia (CAP) were randomized to receive therapy of standard duration (151 patients) or therapy whose duration was guided by procalcitonin (151 patients).
Patients in both groups had an average age of 70 years. Only 20% had antibiotic pretreatment. Most patients in both groups had comorbidities. More than two-thirds of patients had severe or very severe pneumonia.
Among those in the procalcitonin group, patients with levels greater than 0.25 mcg/L were started on antibiotic therapy. Those with levels of 0.25 mcg/L or less were not given antibiotics.
Procalcitonin measurements were performed on all patients on days 0, 2, 4, 6, and 8, though the results were available only for those in the procalcitonin group.
The decision to continue or discontinue antibiotic therapy in the procalcitonin group was based on the cutoff levels described above.
Follow-up, including a chest x-ray, was performed at 4–6 weeks. In patients with clinical uncertainty, there was follow-up remeasurement of procalcitonin in 6 hours.
Patients in the standard therapy group received antibiotics initially, and almost all of them were on antibiotics for more than 8 days. In comparison, only 85% of those in the procalcitonin group initially received antibiotics. In this group, “only about 50% had antibiotics for more than 4 days and about 30% for more than 6 days,” Dr. Christ-Crain said.
Patients in the procalcitonin group received antibiotics for an average of 6 days, compared with 13 days for the standard therapy group. “This is a highly significant reduction of antibiotic use and antibiotic duration,” said Dr. Christ-Crain, at the meeting sponsored by the American Society for Microbiology.
Clinical outcomes—as assessed by using a visual analog scale and clinical parameters such as temperature, oxygen saturation, and pulse rate—were similar in both groups.
Laboratory outcomes—C-reactive protein and procalcitonin levels in the normal reference ranges—assessed at 4–6 weeks were also found to be similar.
Most experts recommend a 10- to 14-day course of antibiotic therapy to treat CAP, but the optimal duration is unknown.
“In our opinion, the correct duration of antibiotics varies from patient to patient,” Dr. Christ-Crain said.
New tests for the determination of procalcitonin levels have improved sensitivity, enabling physicians to distinguish clinically relevant bacterial infections from other infections.
Dr. Christ-Crain and her colleagues demonstrated this in a recent study involving lower respiratory tract infections (Lancet 2004;363:600–7).